安全流媒体存储网络，文件加密分片分布式存取，无需信任节点。
Safecloud: A Distributed, Encrypted Storage Cloud for Streaming
- 文件分块加密后分发至浏览器和服务器，密钥由根密钥派生，仅所有者可解密。
- 支持内容不变则密文相同，实现去重且不暴露明文，节点可盲验完整性。
- 密钥树兼具索引功能，支持视频、音频等多轨独立解密，适合流媒体场景。
我们提出 Safecloud，一个分布式的加密存储与流媒体网络，其存储与路由节点既不查看明文也不持有密钥。每个文件被拆分为块，在所有者设备上加密后，分布于 Drops（浏览器标签中用 IndexedDB 存储密文）和 Jets（联邦路由服务器）。只有所有者或授权人可解密。主要贡献包括：(1) 单根密钥层级结构，所有密钥通过 HKDF 从单一根密钥确定性派生，所有者与范围授权人可达成密钥派生一致；子树密钥仅包含范围信息，无其他泄露（委托隔离）。(2) 收敛式内容寻址：相同内容生成相同密文与标识符，实现去重而无需暴露明文，标识符绑定经认证的密文，使得无密钥的 Drop 可盲验证完整性（盲可验证性）。(3) 在同一导航路径上并行构建三棵哈希树（默克尔树用于完整性，密钥派生树用于机密性，访问控制树用于授权），支持可信的默克尔验证检索。(4) 密钥树同时作为流媒体索引：播放器可在常数时间内推导出每一段密钥，通过派生方式定位；多轨（如视频、音频、字幕）各自为独立子树，可按轨道和段独立解锁，这是目前加密存储网络中尚未实现的组合。(5) Jets 和 Drops 可通过可验证的方式获得 Safebux，通过一种零签名的存储证明挑战机制（冷效应抗腐败证明）保持诚实，形成零和经济模式，成本显著低于 Filecoin 的复制证明封存（速度慢且不提供机密性）。本文给出了架构、密码学构造、威胁模型及开源参考实现，并明确区分了设计与实际实现部分。
原文摘要 · Abstract (English)
We present Safecloud, a distributed, encrypted, self-pricing storage and streaming network whose storage and routing nodes never see plaintext and never hold keys. Each file is split into chunks, encrypted on the owner's device, and distributed across Drops (browser tabs storing ciphertext in IndexedDB) and Jets (federated routing servers). Only the owner, or an authorised grantee, can decrypt. We make five contributions: (1) A one-root key hierarchy: every key derives deterministically from a single root via HKDF, and owner and range-scoped grantee derive identical chunk keys (derivation agreement); a subtree key derives its range and nothing else (delegation containment). (2) Convergent content addressing: identical content yields identical ciphertext and identifiers, enabling deduplication without plaintext exposure, with identifiers binding authenticated ciphertext so a keyless Drop verifies integrity (blind verifiability). (3) Three parallel trees over one navigation path (Merkle for integrity, key-derivation for confidentiality, access for authorisation), with sound Merkle-verified retrieval. (4) The key tree doubles as a streaming index: a player derives each segment key in O(1), seeking by derivation, while parallel tracks (video, audio, captions) are independent subtrees unlockable per-track and per-segment, a combination we believe no prior encrypted-storage network offers. (5) Jets and Drops earn Safebux verifiably, kept honest by a one-signature proof-of-storage challenge under chilling-effect Proof-of-Corruption, a zero-sum economy that is significantly cheaper than Filecoin's proof-of-replication sealing (which is slow and provides no confidentiality). We give the architecture, cryptographic construction, a threat model, and an open-source reference implementation, stating precisely what is implemented versus designed.
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